This study is designed to develop and evaluate a set of non-virologic diagnostic algorithms to monitor HIV-exposed children of unknown infection status for treatment eligibility during the first year of life. The results of this cross sectional study are expected to be used in development of a series of non-virologic algorithms to determining treatment eligibility among HIV-exposed children in settings where polymerase chain reaction (PCR) testing is not available and to guide the judicious use of PCR testing among HIV-exposed children in settings where PCR is available. These results will directly inform program implementation in Zambia.